My OEL6 VM ran out of disk space in its root filesystem, so I had to resize the disk. Most of the howto’s are out-of-date or assume if you’re using cryptsetup you’re using LVM or use GParted which doesn’t handle LUKS, or assumes you’re using ext4 not BTRFS.

Actually it was pretty easy once you ignore all of those incorrect tutorials.

  1. Resize the VirtualBox VDI file to 40Gb:
VBoxManage modifyhd oracle62.vdi --resize 40000
  1. Boot into a Fedora20 LiveCD:
fdisk /dev/sda
delete partition 2 (d)
create new partition 2 (n)
write & quit (w)
  1. When booted back into your VM, resize the BTRFS filesystem to fill you newly grown partition:
btrfs filesystem resize max /
btrfs filesystem defragment /